Metaphyta L ilium. 



163 



closed in their sporophyll ; and since sporangia are deve- 

 loped on both edges, the double row is thus accounted for. 

 When the three carpels are fused together to form one ovary, 

 manifestly the ovules (sporangia) will appear to originate 

 from a central axis, in the formation of which the floral axis, 

 or central part of the cone, may participate. The style, 

 then, is simply the upper part of the sporophylla, the edges 

 of which have not united in the centre, and the trilobed 

 stigma is composed of the terminal points of the same, 

 swollen up and covered with epidermal hairs for a purpose 

 we shall discover presently. 



FIG. 83. -PLACEXTATION. (Prantl.) 



A, one carpel, one loculus ; B, three carpels, one loculus ; c, four carpels, 

 four loculi by upgrowth of thalamus ; D, five carpels, five loculi ; /, 

 placenta. 



Turning now to the sporangium itself we meet with 

 still further differentiation from the type we described in 

 the fern. The sporangium is stalked, but the capsule is 

 doubled down on the funicle, and is adherent to it for a 

 considerable distance. The portion of the funicle which is 

 attached to the sporangium is termed the raphe. A spo- 

 rangium turned upside down thus is said to be anatropal 

 (fig. 84). The sporangium is pear-shaped, its pointed end 

 being directed downwards towards the placenta or point of 

 origin from the sporophyll. The wall of the sporangium is 

 incomplete at this point, and the aperture left is termed 

 the micropyle. The sporangia are not always anatropal. In 

 many plants the sporangium is perfectly straight, with the 

 micropyle pointing upwards (orthotropal) ; in other cases a 

 half-way condition is maintained between the anatropal and 



M 2 



